Rotary abrading tool



Jan. 14, 1958 E. w. HALL ROTARY ABRADING TOOL 2 Sheets-Sheet 1 Filed Aug. 9, 1956 Iweno WHaZZ/, lwf/ gna, P aq VMM Jan. 14, 1958 Elw. HALL 2,819,567

ROTARY ABRADING TOOL Filed Aug. 9, 1956 2 Sheets-Sheet 2 Izzvezao# f E'Zzisa WHaZZ,

United States Patent() ROTARY ABRADING TOOL Elisha Winthrop Hall, Scituate, Mass., assignor to F. L. & J. C. Codman Company, Rockland, Mass., a corporation of Massachusetts Application August 9, 1956, Serial No. 603,091

6 Claims. (Cl. 51-193.5)

This invention relates to a rotary abrading tool of generally cylindrical form which may be a generally unitary element which might be used -alone as a wheeL having -then usually a rather narrow face, or as a constituent of a wheel of relatively broad face consisting of a plurality of such elements suitably arranged side by side.

ln accordance with the invention I provide an element wherein the active surface is made up of a number of spaced, upstanding lingers or strips of flexible sheet material coated with abrasive granules such as emery cloth which fingers while capable of being bent :by contact with the work and which may therefore be called flexible are not flaccid, but when not under pressure extend straight in generally radial directions as implied by the word upstanding.1 The wheel is adapted for heavy work, such as the cutting down and polishing of metal. The element which I am about to describe is light in weight, but strong and adapted to withstand high speed operation and heavy pressure against the object operated on. It is easyand cheap to manufacture. The disposition of the abrasive surfaces is such that the material is economically utilized and -the entire unit may be considered as expendable, economically to be thrown away as a whole when worn.

My invention will be well understood by reference to the following description of the illustrative embodiment thereof shown in the accompanying drawings, wherein:

Fig. l is a partial side elevation of a wheel composed of three elements with parts successively broken away to disclose those elements;

Fig. 2 is a fragmentary section on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary side elevation of the center of the wheel showing one strip in position to be assembled therewith anda second one at the right in posinon;

Fig. 4 is a fragmentary side view, partly broken away, showing the transverse faces of three successive strips illustrating substantially a position which they might assume when the wheel is in use;

Fig. 5 is a diagrammatic edge view of a portion of the wheel, the `ends of the various Strips being shown developed in a straight line and indicated by a single heavy line' Fig. 6 is a similar View, showing the relative positions the outer ends of the strips would takel during use; and

Figs. 7, 8 and 9 are views of different forms of abrasive coated strips. t

I have indicated the abrasive character of the strips by stippling, but have limited the stippling to small areas to avoid `an inartistic effect. Also, since the disclosure is of a wheel involving three elements of identical form, I have sometimes appended to a reference numeral the letters n, c and o, suggestive, respectively, of the words nigh, center and 05, where it would aid in the description, but have also used the reference numeral without any additional letter where it has a genenc application in the context.

l wardly beyond the same.

2,819,567 Patented Jan. 14, 1958 ICC Referring now to the drawings. Each element, and it will be recalled that a single element may be used alone as an abrading wheel, may comprise a center in the form of a circular disc 20, desirably formed from fiber board or binders board. I do not use these words in any technical sense except insofar as, like the word cardboard they suggest a relatively cheap and expendable material such as may be made from agglomerated libers. The word board suggests a certain substantial thickness, although `small in comparison with superficial area. The element has a central opening 22 to receive a shaft. At suitable intervals around the periphery of the board it is slotted and of course, as best seen in Fig. 3, the slots 24 preferably being arranged at a slight angle to the radial, as indicated. In these slots are mounted what I will here refer to as strips of flexible material coated with abrasive granules, in the nature of emery cloth or sandpaper. Usually a woven cloth will be utilized. The strips 26J considered as a whole, are of substantially greater width than `the thickness of the center 20, and their lengthis greater than their width.

In Fig. 3 at the left is seen a two-ply strip 26, consisting of two pieces of abrasive coated material positioned ad jacent one of the Slots 24 in the center 20, ready to be entered into the slot. At the right a strip has been so entered and the marginal portions thereof 28 at the inner end are folded back against the faces of the center 20, preferably without severance from the marginal portions further out. The parts are secured together by suitable adhesive. In this instance it will be seen that the strip is broughtinto a `generally channeled form, but as it is not sharply creased it will flare toward the outer end, the whole finger being, when not under stress, of a somewhat channeled form. The projecting strips are in a sense closely arranged but nevertheless spaced and independent at their other ends when not stressed against the work. When the slots have been filled with ngers in this manner, sideplates 30, which may be of relatively thin and dense fibrous material in the nature of pressboard, are glued to the sides of the center 20 and project over the margins 2S of the strips. lf the wheel is mounted on a shaft between end `plates in the customary manner the end plates will press against the outer periphery of the center where the side portions of the strips 26 are folded down on the same and aid in holding the latter. If we imagine the wheel to be turned clockwise viewing Fig. 3, the righthandface of the projecting strip will sweep over the work and it will be bent backwards and flattened `out in the manner illustrated in Fig. 4,\to be supported by the following strip which projects rear- Whi'le the outer portions lie substantially at to engage the work as a broad wiping surface they are supported by a sort of central stem bracedby gussets formed by the folded over marginal portions where they extend into the planes of the sides of center disc Ztl. t If the wheel moves clockwise viewing Fig. 4, the gussets are in compression. It, run in the opposite direction they are in tension.

When in use the strips press against the work with resilient elasticity. The density of the wheel may be varied by varying the number of elements. The number Uwill -vary with the` circumference of center disc 20, but it should be emphasized `that the fingers are not packed together as if the wheel were formed of transverse laminations. Neitherare they so widely spaced as to be substantially independent merely acting lin succession. Each acts individually but in cooperation with others.

sure on the work. The number of plies in a strip also' has its inuence on the character of the wheel since the resistance of the strip to bending will vary with the number.

When multi-ply strips are used, whether separate or bonded together, the faces presented in the same direction may be coated with abrasive. The strip wears by disintegration of the abrasive coating. As the granules are worn down or broken away the adhesive bonding layer is broken down and the underlying threadbare fabric will then rapidly disintegrate in turn and the abrasive surface of the underlying ply will then come into action.

It will be noted from Fig. 3 that the corners of the slots are shown as rounded over. This facilitates the insertion of the strips and avoids bending them over a sharp corner when in use. The reason for angling the slots as already referred to is to throw the corners. of the inner end of the rectangular strip inwardly toward the center to provide a greater area for adhesive bonding to the center disc 20.

A wheel of relatively wide face may be made by assembling a plurality of elements, three being illustrated in Figs. 1 and 2, wherein the parts are identified by reference numerals modified by the letter n for the nigh or nearest element viewing Fig. 1, the letter c for the middle element and the letter o for the off or furthest element. When two or more elements are utilized to make a wheel, the projecting strips of adjacent discs are positioned so as to be offset circumferentially and will have the disposition illustrated in Fig. 5, wherein when the parts are unstressed the lateral lingers to a certain extent overlap in the circumferential direction with the central group of fingers to give a relatively dense arrangement at the periphery of the wheel, and provide mutual support between the various fingers. As the ends of the fingers are attened out in use their relative positions will be approximately as indicated diagrammatically in Fig. 6.

The strips used may be coated on one or both sides. In Fig. 3 I have shown a two-ply strip, consisting of two, at least originally entirely separate, plies which, however, in this particular instance are of the same width and length. Two plies might be formed by doubling a longer strip, and if the fold were placed at the outer end as illustrated by the strip 26a in Fig. 7, fraying at the end is retarded.

In Fig. 7 I have indicated diagrammatically on the broken-away part of the strip 26a that the cloth is cut on the bias. This may be desirable in some instances.

In Fig. 8 I have shown a strip 26h having coarse granules on the nearer face, and finger granules on the further face, as indicated by the finer stippling. A wheel of this nature may be merely reversed to provide different cutting characteristics, and this may be a particularly desirable arrangement for small users.

In Fig. 9 the strip 26d consists of a relatively wide strip with a narrower central strip superposed thereon, either loosely or secured by adhesive. The strip is treated as a unit with its inner end mounted on one of the slots 24.

While exact dimensions are in no Way essential to the invention, it may be helpful to state that the present drawings illustrate a Wheel of about 8% external diameter, wherein the center 20 is about 41/2 in diameter and constructed of a single piece of fiberboard about 1A thick. v The pressboard sideplates are 1&2" thick. The abrasive coated strips are 2%" long and about 11/2 wide and are received in slots 1/2 deep, twenty in number.

The resilient character of the element adapts it to work of irregular contour. It also may be used as a radial face wheel to operate on the wall of a slot. The adhesive f coated material of which the fingers are made is expensive. The construction provides for bringing a large area into play and for economical utilization of at least a major portion of abrasive in the material used. When supported as described and when so efficiently utilized, it is economically practical to discard the entire element when worn and to replace it.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular embodiment described and which I desire to secure by Letters Patent.

I claim:

l. A rotary abrading element comprising a board of agglomerated fibers in the form of a disc formed for mounting on a rotary driver to turn about its center, the disc having a series of slots transversely across its periphery, and upstanding strips of flexible sheet material coated with abrasive granules adherent thereon, the width of the strips being substantially greater than the thickness of the disc and having their inner end portions fitted into the slots, the margins of said end portions being folded over on the end faces of the disc and adhesively secured thereto with free outer portions of the strips projecting beyond the disc.

2. A rotary abrading element as set forth in claim 1 wherein thin end plates of dense fiber are adhesively secured to the faces of the disc and said folded over margins.

3. A rotary abrading element as set forth in claim l wherein said margins are folded in the same direction to give at least the inner portion of the strip a generally channeled form with uninterrupted edges of the strips extending from the projecting portion thereof into the planes of the side faces of the disc.

4. A rotary abrading wheel comprising a plurality of axially juxtaposed elements, each including a board of agglomerated fibers in the form of a disc, and upstanding strips of flexible sheet material having a coating of abrasive granules adherent thereon, said strips being of a width substantially greater than the thickness of the disc and having the central portions of their inner ends disposed crosswise of the disc and secured thereto at intervals therearound and with free, upstanding portions projecting outward from the disc and laterally therefrom to either side thereof in planes angular to the central plane of the disc.

5. A rotary abrading element comprising a board of agglomerated fibers in the form of a disc and formed for mounting on a rotary driver for turning about its center, upstanding strips of flexible sheet material having a coating of abrasive granules adherent thereto, the strips being of a width substantially greater than the thickness of the disc and having the central portions of their inner ends disposed crosswise of the disc and secured thereto at intervals therearound and with free, upstanding portions projecting outward from the disc and laterally therefrom to either side vthereof in planes angular to the central plane of the disc.

6. A rotary abrading element as set forth in claim 5 wherein the strips are formed of more than one ply.

References Cited in the file of this patent UNITED STATES PATENTS 81,986 Crane Sept. 8, 1868 2,146,548 Mitschang et al. Feb. 7, 1939 2,444,093 Crumbling et al June 29, 1948 2,642,705 Jensen June 23, 1953 

